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(revised 07/13/2011) . |
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(revised 07/13/2011) . |
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Poster: Mineral geochemistry and petrogenesis of granitic pegmatites in the Fregeneda-Almendra area (Spain and Portugal), by Vieira, R., Roda-Robles, E., Pesquera, A., and Lima, A. Poster: Mineral geochemistry and petrogenesis of granitic pegmatites in the Fregeneda-Almendra area (Spain and Portugal) in pdf format: The Fregeneda-Almendra pegmatite field (Spain-Portugal) is characterized by the occurrence of numerous pegmatites of different types. Most of these pegmatites are barren, but Li- and/or Sn-rich bodies are also abundant in the northern part of the field. These pegmatites intruded mainly the Schist- Greywacke Complex, north of the syn- to late-Variscan Mêda-Penedono-Lumbrales leucogranite complex (MPL). They show a zonal distribution with the degree of evolution increasing northwards relative to the MPL. In order to shed light on the genetic relationships between granites and pegmatites in the FA field, representative micas from the muscovite-lepidolite series were separated from the different pegmatite types, as well as from the MPL granitic complex and from another granite detected by drills in the north of the area. These mica samples have been used to date their hosting rocks by the step-heating 40Ar/39Ar method. Moreover, a geochemical modelization has been made in order to define the possible evolutionary trends, and the petrogenetic affiliation of the different pegmatite types, as well as the relationships between the pegmatites. A first event of pegmatite formation would be related to the crystallization of the syn- to late-D3 Variscan MPL granitic complex. The trace-element modeling shows that lower rates of fractional crystallization, from a melt with similar composition to the MPL, would originate the barren intragranitic pegmatites and the granitic apophysis that outcrop close to the MPL, whereas higher degrees of fractional crystallization would be related to the origin of the Sn-rich dykes of the Feli open pit. These bodies, with plateau ages ranging between 300.0 ± 3.5 to 304.8 ± 4.4 Myr, intruded S3 tectonic foliations (N100-120E) and are connected to the Variscan polyharmonic folding and to the MPL emplacement. The generation of some conformable metamorphic and granitic-pegmatitic segregations that outcrop in the proximities of the MPL, considered to form part of the Alamo Complex, would be coetaneous or preceding this process. The discordant intermediate and the Li-rich pegmatites represent highly differentiated melts, enriched in rare-elements, especially lithium. They infill late-tectonic Variscan sinistral structures (NNE-SSW and NE-SW), with plateau ages ranging from 295.1 ± 4.2 to 296.4 ± 3.5 Myr. The trace-element modeling demonstrate that these pegmatites would be related to high rates (≥ 90%) of fractional crystallization from melts with compositions analogous to the late- to post-D3 Variscan granites, e.g., Saucelle or Villar de Ciervo granites, respectively. However, the difference of 10 Myr in the age between the late-D3 Variscan granites and these pegmatites, exclude those granites as potential generators of the Li-rich pegmatites. Accordingly, the evolved pegmatites could be related to a late-Variscan (300 to 280 Myr) non-outcropping granite as a result of high rates (≥ 90%) of fractional crystallization.
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The 5th International Symposium on the Granitic Pegmatites, Mendoza, Argentina, February 20-27, 2011 The 5th International Symposium on Granitic Pegmatites was held in Mendoza, Argentina. There were 4 invited speakers: D. London, R. Martin, M. Novak and W. Simmons, 29 oral conferences and 26 posters all related to different pegmatology disciplines: mineralogy (28), geochemistry (10), petrology and petrogenesis (21). The 125 authors, representing 5 continents, sent their contributions and more than half of them attended the symposium. The second day of the conference was dedicated to celebrate and honor the life-long academic path of Dr. Petr Cerny. There was a post-symposium Field Trip (February 24-27) to the San Luis ranges, which permitted the observation, discussion and sampling of different types of granitic pegmatites outcropping in the southern districts of the Pampean pegmatite province. Part of the field trip consisted in the visit to the Milling plant where feldspar and quartz from different pegmatites of the region are processed: P G La Toma. There was a guided visit to the plant. Technical Program, Contributions, and Field Trip Guidebook in pdf format:
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Field Course on the Rare Element Pegmatites of Madagascar, June 11 - 22, 2001, Antananarivo, Madagascar. Organized by Museum of Natural History, Milan (Italy), University of New Orleans, Dept. of Geology & Geophysics (LA – USA) Direction of the Geological Survey, Ministry of Energy and Mines, Antananarivo (Madagascar) with the collaboration of ATPEM (Assistance Technique aux Petits Exploitants Miniers), Direction des Mines et de la Géologie, Antananarivo (Madagascar) Gondwana Gems, Antananarivo (Madagascar). Organizing Co-Sponsors: S.N.T.P. International, Group CFE, Antananarivo (Madagascar). UNESCO-IUGS-IGCP. Technical Program And Field Trip Guidebook in pdf format:
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The new discovery of a LCT pegmatite in the Adamello massif, Central Southern Alps, Italy. by Federico Pezzotta & Alessandro Guastoni, Museo Civico di Storia Naturale, Corso Venezia 55, 20121 Milan, Italy. in pdf format: |
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Active Gem Mining at the Cryo Genie Pegmatite Mine, southern California by Jim Clanin, JC Mining (Reports 1-8); Kenneth L. Gochenour (Report 9) in pdf format: Report 1 (Aug 1, 2002): text + 3 figures (180K) Report 2 (Sept 1, 2002): text (56K) Report 3 (Sept 7, 2002): text + 2 figs. (108K) Report 4 (Sept 13, 2002): text (48K) Report 5 (Sept 21, 2002): text (83K) Report 6 (Sept 29, 2002): text + 3 figs. (560K) Report 7 (Oct 27, 2002): text + 2 figs. (150K) Report 8 (Nov, 2002): text + 2 figs. (132K) Report 9 (Sept, 2002): text + 4 figs. (180K) |
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The Anjahamiary pegmatite, Fort Dauphin area, Madagascar. by Federico Pezzotta , Museo Civico di Storia Naturale, Corso Venezia 55, 20121 Milan, Italy and Marc Jobin, SOMEMA, BP 6018, Antananarivo 101, Madagascar. in pdf format: |
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Application of Ground Penetrating Radar (GPR) at the Cyro-Genie Gem Pegmatite Mine, San Diego County, California by Jeffrey E. Patterson, University of Calgary, Calgary, AB, Canada. Mining continues through 2003 at the Cryo-Genie mine, near Warner Springs, California, and large, crystal-filled miarolitic cavities are still being discovered. To aid in the exploration for pockets, Jeffrey Patterson conducted a survey by ground penetrating radar (GPR), and his recently published report is available here in pdf format: |
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Spessartine from Navegador, Minas Gerais, Brazil: Etch or Growth Features? by David London, School of Geology & Geophysics, University of Oklahoma, Norman, OK 73019 USA e-mail: dlondon@ou.edu. in html format: in pdf format: Postscript: Spessartine from Navegador, Minas Gerais, Brazil: Etch or Growth Features? in html format: in pdf format: |
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Petrography and Geochemistry of the Li-F Granites and Aplite-Pegmatoid Banded Rocks of the Orlovka and Etyka Tantalum Deposits in the East Transbaikalia by G.P. Zaraisky (1), R. Seltmann (2), V.V. Shatov (3), A.M. Aksyuk, Yu.B. Shapovalov (1), and V.Yu. Chevychelov (1) in html format: in pdf format: |
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Exceptional Chiavennite Associated with Pezzottaite from the Sakavalana Pegmatite, Ambatovita, Madagascar by Federico Pezzotta(1), Alessandro Guastoni(1), Herve Forner(2),
Francesco Demartin(3), and Roy Kristiansen(4) in html format: in pdf format: |
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Mining News from Mt. Mica, Maine - 2004 Gary Freeman in html format: in pdf format: |
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Mining News from Mt. Mica, Maine - 2005 Gary Freeman in html format: in pdf format: |
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Mining News from Mt. Mica, Maine - 2006 Gary Freeman in html format: in pdf format: |
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Crystallization Processes in Granitic Pegmatites General Information (pdf) (344K) List of Participants (pdf) (80K) Field Program (pdf) (376K) Figure Captions and Links to Photos (html) (4K) List of Abstracts with Links (html) (4K) |
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